diff --git a/tests/phpunit/CiteTest.php b/tests/phpunit/CiteTest.php
new file mode 100644
index 000000000..87a1e3278
--- /dev/null
+++ b/tests/phpunit/CiteTest.php
@@ -0,0 +1,41 @@
+<?php
+
+use Wikimedia\TestingAccessWrapper;
+
+/**
+ * @coversDefaultClass \Cite
+ */
+class CiteTest extends MediaWikiTestCase {
+
+	protected function setUp() : void {
+		parent::setUp();
+
+		$this->setMwGlobals( [
+			'wgFragmentMode' => [ 'html5' ],
+		] );
+	}
+
+	/**
+	 * @covers ::normalizeKey
+	 * @dataProvider provideKeyNormalizations
+	 */
+	public function testNormalizeKey( $key, $expected ) {
+		/** @var Cite $cite */
+		$cite = TestingAccessWrapper::newFromObject( new Cite() );
+		$this->assertSame( $expected, $cite->normalizeKey( $key ) );
+	}
+
+	public function provideKeyNormalizations() {
+		return [
+			[ 'a b', 'a_b' ],
+			[ 'a  __  b', 'a_b' ],
+			[ ':', ':' ],
+			[ "\t\n", '&#9;&#10;' ],
+			[ "'", '&#039;' ],
+			[ "''", '&#039;&#039;' ],
+			[ '"%&/<>?[]{|}', '&quot;%&amp;/&lt;&gt;?&#91;&#93;&#123;&#124;&#125;' ],
+			[ 'ISBN', '&#73;SBN' ],
+		];
+	}
+
+}